[yt-users] Making averaged line plot.

[Suoqing Ji]

Hi Yuxiao,

If you would like to start from your current code, the most straightforward way is to write a loop to smooth over a certain distance by each step, which also works for AMR data:

smooth_len = 100 # smoothing length of 100 kpc
SmoothedBMag = np.copy(ray[’ScaledBMag’]) # store the smoothed array
bin_num = np.ceiling((ray[‘x’].max() - ray[‘x’].min()) / smooth_len) # make bins every 100 kpc

for step in range(bin_num):
    mask1 = (ray[‘x’] >= ray[‘x’].min() + step * smooth_len)
    mask2 = (ray[‘x’] < ray[‘x’].min() + (step + 1) * smooth_len)
    mask = np.logical_and(mask1, mask2) # mask the cells within a certain length of 100 kpc
    SmoothedBMag[mask] = np.mean(ray[’ScaledBMag’][mask]) # take the average and save

After that the array “SmoothedBMag” is the smoothed one.

However, an easier way is to use the the 1D ProfilePlot function (http://yt-project.org/docs/2.6/visualizing/plots.html#d-profile-plots <http://yt-project.org/docs/2.6/visualizing/plots.html#d-profile-plots>), and in this case you could do something like:

plot = ProfilePlot(pf.h.all_data(), ‘x’, [’ScaledBMag’], n_bins=bin_num)

Note that this will do the average over entire y-z plane for each x bins, which is different from averaging only an array of a ray object (so maybe it’s not what you want). If you really want the data within a thin slit only, you could define a region object pf.h.region() and do ProfilePlot. I think it’s also doable to use the function “load_uniform_grid” to create a 1D dataset from the arrays in ray object and pass it to ProfilePlot.

Best wishes,
--
Suoqing JI
Ph.D Candidate
Department of Physics
University of California, Santa Barbara
http://web.physics.ucsb.edu/~suoqing

> On Mar 14, 2016, at 10:57 PM, Yuxiao Dai <yuxiao.dai at nyu.edu> wrote:
> 
> Dear all, 
> 
> I have a line plot of some parameter along an axis as a function of distance. Now I would like to get another line plot of the same parameter but averaged over a certain distance (say 100 kpc, the plot below is supposed to be flat after this). I've been searching the document for some time but haven't found a method. Is there a simple way to do this? 
> 
> I would very much appreciate it if anyone could help me on this. 
> 
> 
> ===================================
> import ...
> 
> def _ScaledBMag(field, data):
> 
>     return ...
> 
> 
> 
> ....
> 
> pf = load(filename)
> 
>     add_field("ScaledBMag", function=_ScaledBMag)
> 
> 
> 
>     c = pf.h.find_max('ScaledBMag')[1]
> 
>     ax = 0
> 
>     ray = pf.h.ortho_ray(ax, (c[1], c[2]))
> 
>     
>     P.subplot(211)
> 
>     P.semilogy(ray['x'], ray['ScaledBMag'])
> 
>     P.xlabel('x')
> 
>     P.ylabel('ScaledBMag')
> 
>     print "works"
> 
>     P.savefig("ScaledBMag_lineplot.png")
> 
> 
> <image.png>
> 
> ===================================
> I'm using yt
> 
> Version = 2.6.1
> 
> 
> Changeset = c994959ed3be
> 
> ===================================
> 
> 
> 
> 
> 
> Regards,
> 
> Dai 
> 
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> yt-users mailing list
> yt-users at lists.spacepope.org
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